In the proposed work we plan to study further the action of glucocorticoids (dexamethasone) on the structure and function of hepatic subcellular organelles. In one aspect of this study the effect of glucocorticoids on proliferation of endoplasmic reticulum (ER) in hepatocytes will be investigated. Rough and smooth microsomes will be prepared from liver and the microsomal membranes will be further "purified" by removing ribosomes, adsorbed proteins, and vesicular proteins. In corporation of radioactive leucine and glycerol into membrane proteins and lipids will be determined by injecting these precursors into rats and at appropriate time-intervals, removing the livers and preparing the ER membranes. Comparisons of the radioactivity in the purified rough and smooth membranes from normal fasted and fed rats, adrenalectomized animals, and adrenalectomized, dexamethasone-treated rats will be made. Another aspect of this study will involve subcellular localization of enzymes involved in glycogen metabolism. Smooth and rough microsomes, as well as the soluble components of the cytosome, will be iosolated and assayed for their content of phosphorylase, glycogen synthase, kinase, and synthase phosphatase in fasted and fed rats; and in adrenalectomized and adrenalectomized, glucocorticoid-treated animals. BIBLIOGRAPHIC REFERENCES: Friedman, H.I. and Robert R. Cardell, Jr. 1977 Alterations in the morphology of the endoplasmic reticulum and Golgi complex in intestinal epithelial cells during fat absorption and after termination of this process: A morphological and morphometric study, In Press. Anat. Rec. Sadler, T.W. an Robert R. Cardell, Jr. 1977 Ultrastructural alterations in neuroepithelial cells of mouse embryos to cytotoxic doses of hydroxyurea, In Press. Anat. Rec.